diff options
| -rw-r--r-- | Documentation/vm/hmm.rst | 54 | ||||
| -rw-r--r-- | drivers/gpu/drm/nouveau/nouveau_dmem.c | 122 | ||||
| -rw-r--r-- | include/linux/migrate.h | 118 | ||||
| -rw-r--r-- | mm/migrate.c | 244 |
4 files changed, 194 insertions, 344 deletions
diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst index e63c11f7e0e0..0a5960beccf7 100644 --- a/Documentation/vm/hmm.rst +++ b/Documentation/vm/hmm.rst @@ -339,58 +339,8 @@ Migration to and from device memory =================================== Because the CPU cannot access device memory, migration must use the device DMA -engine to perform copy from and to device memory. For this we need a new -migration helper:: - - int migrate_vma(const struct migrate_vma_ops *ops, - struct vm_area_struct *vma, - unsigned long mentries, - unsigned long start, - unsigned long end, - unsigned long *src, - unsigned long *dst, - void *private); - -Unlike other migration functions it works on a range of virtual address, there -are two reasons for that. First, device DMA copy has a high setup overhead cost -and thus batching multiple pages is needed as otherwise the migration overhead -makes the whole exercise pointless. The second reason is because the -migration might be for a range of addresses the device is actively accessing. - -The migrate_vma_ops struct defines two callbacks. First one (alloc_and_copy()) -controls destination memory allocation and copy operation. Second one is there -to allow the device driver to perform cleanup operations after migration:: - - struct migrate_vma_ops { - void (*alloc_and_copy)(struct vm_area_struct *vma, - const unsigned long *src, - unsigned long *dst, - unsigned long start, - unsigned long end, - void *private); - void (*finalize_and_map)(struct vm_area_struct *vma, - const unsigned long *src, - const unsigned long *dst, - unsigned long start, - unsigned long end, - void *private); - }; - -It is important to stress that these migration helpers allow for holes in the -virtual address range. Some pages in the range might not be migrated for all -the usual reasons (page is pinned, page is locked, ...). This helper does not -fail but just skips over those pages. - -The alloc_and_copy() might decide to not migrate all pages in the -range (for reasons under the callback control). For those, the callback just -has to leave the corresponding dst entry empty. - -Finally, the migration of the struct page might fail (for file backed page) for -various reasons (failure to freeze reference, or update page cache, ...). If -that happens, then the finalize_and_map() can catch any pages that were not -migrated. Note those pages were still copied to a new page and thus we wasted -bandwidth but this is considered as a rare event and a price that we are -willing to pay to keep all the code simpler. +engine to perform copy from and to device memory. For this we need to use +migrate_vma_setup(), migrate_vma_pages(), and migrate_vma_finalize() helpers. Memory cgroup (memcg) and rss accounting diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c index 345c63cb752a..38416798abd4 100644 --- a/drivers/gpu/drm/nouveau/nouveau_dmem.c +++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c @@ -131,9 +131,8 @@ nouveau_dmem_fault_alloc_and_copy(struct vm_area_struct *vma, unsigned long *dst_pfns, unsigned long start, unsigned long end, - void *private) + struct nouveau_dmem_fault *fault) { - struct nouveau_dmem_fault *fault = private; struct nouveau_drm *drm = fault->drm; struct device *dev = drm->dev->dev; unsigned long addr, i, npages = 0; @@ -230,14 +229,9 @@ error: } } -void nouveau_dmem_fault_finalize_and_map(struct vm_area_struct *vma, - const unsigned long *src_pfns, - const unsigned long *dst_pfns, - unsigned long start, - unsigned long end, - void *private) +static void +nouveau_dmem_fault_finalize_and_map(struct nouveau_dmem_fault *fault) { - struct nouveau_dmem_fault *fault = private; struct nouveau_drm *drm = fault->drm; if (fault->fence) { @@ -257,29 +251,35 @@ void nouveau_dmem_fault_finalize_and_map(struct vm_area_struct *vma, kfree(fault->dma); } -static const struct migrate_vma_ops nouveau_dmem_fault_migrate_ops = { - .alloc_and_copy = nouveau_dmem_fault_alloc_and_copy, - .finalize_and_map = nouveau_dmem_fault_finalize_and_map, -}; - static vm_fault_t nouveau_dmem_migrate_to_ram(struct vm_fault *vmf) { struct nouveau_dmem *dmem = page_to_dmem(vmf->page); unsigned long src[1] = {0}, dst[1] = {0}; + struct migrate_vma args = { + .vma = vmf->vma, + .start = vmf->address, + .end = vmf->address + PAGE_SIZE, + .src = src, + .dst = dst, + }; struct nouveau_dmem_fault fault = { .drm = dmem->drm }; - int ret; /* * FIXME what we really want is to find some heuristic to migrate more * than just one page on CPU fault. When such fault happens it is very * likely that more surrounding page will CPU fault too. */ - ret = migrate_vma(&nouveau_dmem_fault_migrate_ops, vmf->vma, - vmf->address, vmf->address + PAGE_SIZE, - src, dst, &fault); - if (ret) + if (migrate_vma_setup(&args) < 0) return VM_FAULT_SIGBUS; + if (!args.cpages) + return 0; + + nouveau_dmem_fault_alloc_and_copy(args.vma, src, dst, args.start, + args.end, &fault); + migrate_vma_pages(&args); + nouveau_dmem_fault_finalize_and_map(&fault); + migrate_vma_finalize(&args); if (dst[0] == MIGRATE_PFN_ERROR) return VM_FAULT_SIGBUS; @@ -648,9 +648,8 @@ nouveau_dmem_migrate_alloc_and_copy(struct vm_area_struct *vma, unsigned long *dst_pfns, unsigned long start, unsigned long end, - void *private) + struct nouveau_migrate *migrate) { - struct nouveau_migrate *migrate = private; struct nouveau_drm *drm = migrate->drm; struct device *dev = drm->dev->dev; unsigned long addr, i, npages = 0; @@ -747,14 +746,9 @@ error: } } -void nouveau_dmem_migrate_finalize_and_map(struct vm_area_struct *vma, - const unsigned long *src_pfns, - const unsigned long *dst_pfns, - unsigned long start, - unsigned long end, - void *private) +static void +nouveau_dmem_migrate_finalize_and_map(struct nouveau_migrate *migrate) { - struct nouveau_migrate *migrate = private; struct nouveau_drm *drm = migrate->drm; if (migrate->fence) { @@ -779,10 +773,15 @@ void nouveau_dmem_migrate_finalize_and_map(struct vm_area_struct *vma, */ } -static const struct migrate_vma_ops nouveau_dmem_migrate_ops = { - .alloc_and_copy = nouveau_dmem_migrate_alloc_and_copy, - .finalize_and_map = nouveau_dmem_migrate_finalize_and_map, -}; +static void nouveau_dmem_migrate_chunk(struct migrate_vma *args, + struct nouveau_migrate *migrate) +{ + nouveau_dmem_migrate_alloc_and_copy(args->vma, args->src, args->dst, + args->start, args->end, migrate); + migrate_vma_pages(args); + nouveau_dmem_migrate_finalize_and_map(migrate); + migrate_vma_finalize(args); +} int nouveau_dmem_migrate_vma(struct nouveau_drm *drm, @@ -790,40 +789,45 @@ nouveau_dmem_migrate_vma(struct nouveau_drm *drm, unsigned long start, unsigned long end) { - unsigned long *src_pfns, *dst_pfns, npages; - struct nouveau_migrate migrate = {0}; - unsigned long i, c, max; - int ret = 0; - - npages = (end - start) >> PAGE_SHIFT; - max = min(SG_MAX_SINGLE_ALLOC, npages); - src_pfns = kzalloc(sizeof(long) * max, GFP_KERNEL); - if (src_pfns == NULL) - return -ENOMEM; - dst_pfns = kzalloc(sizeof(long) * max, GFP_KERNEL); - if (dst_pfns == NULL) { - kfree(src_pfns); - return -ENOMEM; - } + unsigned long npages = (end - start) >> PAGE_SHIFT; + unsigned long max = min(SG_MAX_SINGLE_ALLOC, npages); + struct migrate_vma args = { + .vma = vma, + .start = start, + }; + struct nouveau_migrate migrate = { + .drm = drm, + .vma = vma, + .npages = npages, + }; + unsigned long c, i; + int ret = -ENOMEM; + + args.src = kzalloc(sizeof(long) * max, GFP_KERNEL); + if (!args.src) + goto out; + args.dst = kzalloc(sizeof(long) * max, GFP_KERNEL); + if (!args.dst) + goto out_free_src; - migrate.drm = drm; - migrate.vma = vma; - migrate.npages = npages; for (i = 0; i < npages; i += c) { - unsigned long next; - c = min(SG_MAX_SINGLE_ALLOC, npages); - next = start + (c << PAGE_SHIFT); - ret = migrate_vma(&nouveau_dmem_migrate_ops, vma, start, - next, src_pfns, dst_pfns, &migrate); + args.end = start + (c << PAGE_SHIFT); + ret = migrate_vma_setup(&args); if (ret) - goto out; - start = next; + goto out_free_dst; + + if (args.cpages) + nouveau_dmem_migrate_chunk(&args, &migrate); + args.start = args.end; } + ret = 0; +out_free_dst: + kfree(args.dst); +out_free_src: + kfree(args.src); out: - kfree(dst_pfns); - kfree(src_pfns); return ret; } diff --git a/include/linux/migrate.h b/include/linux/migrate.h index 7f04754c7f2b..18156d379ebf 100644 --- a/include/linux/migrate.h +++ b/include/linux/migrate.h @@ -182,107 +182,27 @@ static inline unsigned long migrate_pfn(unsigned long pfn) return (pfn << MIGRATE_PFN_SHIFT) | MIGRATE_PFN_VALID; } -/* - * struct migrate_vma_ops - migrate operation callback - * - * @alloc_and_copy: alloc destination memory and copy source memory to it - * @finalize_and_map: allow caller to map the successfully migrated pages - * - * - * The alloc_and_copy() callback happens once all source pages have been locked, - * unmapped and checked (checked whether pinned or not). All pages that can be - * migrated will have an entry in the src array set with the pfn value of the - * page and with the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set (other - * flags might be set but should be ignored by the callback). - * - * The alloc_and_copy() callback can then allocate destination memory and copy - * source memory to it for all those entries (ie with MIGRATE_PFN_VALID and - * MIGRATE_PFN_MIGRATE flag set). Once these are allocated and copied, the - * callback must update each corresponding entry in the dst array with the pfn - * value of the destination page and with the MIGRATE_PFN_VALID and - * MIGRATE_PFN_LOCKED flags set (destination pages must have their struct pages - * locked, via lock_page()). - * - * At this point the alloc_and_copy() callback is done and returns. - * - * Note that the callback does not have to migrate all the pages that are - * marked with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration - * from device memory to system memory (ie the MIGRATE_PFN_DEVICE flag is also - * set in the src array entry). If the device driver cannot migrate a device - * page back to system memory, then it must set the corresponding dst array - * entry to MIGRATE_PFN_ERROR. This will trigger a SIGBUS if CPU tries to - * access any of the virtual addresses originally backed by this page. Because - * a SIGBUS is such a severe result for the userspace process, the device - * driver should avoid setting MIGRATE_PFN_ERROR unless it is really in an - * unrecoverable state. - * - * For empty entry inside CPU page table (pte_none() or pmd_none() is true) we - * do set MIGRATE_PFN_MIGRATE flag inside the corresponding source array thus - * allowing device driver to allocate device memory for those unback virtual - * address. For this the device driver simply have to allocate device memory - * and properly set the destination entry like for regular migration. Note that - * this can still fails and thus inside the device driver must check if the - * migration was successful for those entry inside the finalize_and_map() - * callback just like for regular migration. - * - * THE alloc_and_copy() CALLBACK MUST NOT CHANGE ANY OF THE SRC ARRAY ENTRIES - * OR BAD THINGS WILL HAPPEN ! - * - * - * The finalize_and_map() callback happens after struct page migration from - * source to destination (destination struct pages are the struct pages for the - * memory allocated by the alloc_and_copy() callback). Migration can fail, and - * thus the finalize_and_map() allows the driver to inspect which pages were - * successfully migrated, and which were not. Successfully migrated pages will - * have the MIGRATE_PFN_MIGRATE flag set for their src array entry. - * - * It is safe to update device page table from within the finalize_and_map() - * callback because both destination and source page are still locked, and the - * mmap_sem is held in read mode (hence no one can unmap the range being - * migrated). - * - * Once callback is done cleaning up things and updating its page table (if it - * chose to do so, this is not an obligation) then it returns. At this point, - * the HMM core will finish up the final steps, and the migration is complete. - * - * THE finalize_and_map() CALLBACK MUST NOT CHANGE ANY OF THE SRC OR DST ARRAY - * ENTRIES OR BAD THINGS WILL HAPPEN ! - */ -struct migrate_vma_ops { - void (*alloc_and_copy)(struct vm_area_struct *vma, - const unsigned long *src, - unsigned long *dst, - unsigned long start, - unsigned long end, - void *private); - void (*finalize_and_map)(struct vm_area_struct *vma, - const unsigned long *src, - const unsigned long *dst, - unsigned long start, - unsigned long end, - void *private); +struct migrate_vma { + struct vm_area_struct *vma; + /* + * Both src and dst array must be big enough for + * (end - start) >> PAGE_SHIFT entries. + * + * The src array must not be modified by the caller after + * migrate_vma_setup(), and must not change the dst array after + * migrate_vma_pages() returns. + */ + unsigned long *dst; + unsigned long *src; + unsigned long cpages; + unsigned long npages; + unsigned long start; + unsigned long end; }; -#if defined(CONFIG_MIGRATE_VMA_HELPER) -int migrate_vma(const struct migrate_vma_ops *ops, - struct vm_area_struct *vma, - unsigned long start, - unsigned long end, - unsigned long *src, - unsigned long *dst, - void *private); -#else -static inline int migrate_vma(const struct migrate_vma_ops *ops, - struct vm_area_struct *vma, - unsigned long start, - unsigned long end, - unsigned long *src, - unsigned long *dst, - void *private) -{ - return -EINVAL; -} -#endif /* IS_ENABLED(CONFIG_MIGRATE_VMA_HELPER) */ +int migrate_vma_setup(struct migrate_vma *args); +void migrate_vma_pages(struct migrate_vma *migrate); +void migrate_vma_finalize(struct migrate_vma *migrate); #endif /* CONFIG_MIGRATION */ diff --git a/mm/migrate.c b/mm/migrate.c index 8992741f10aa..8111e031fa2b 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -2118,16 +2118,6 @@ out_unlock: #endif /* CONFIG_NUMA */ #if defined(CONFIG_MIGRATE_VMA_HELPER) -struct migrate_vma { - struct vm_area_struct *vma; - unsigned long *dst; - unsigned long *src; - unsigned long cpages; - unsigned long npages; - unsigned long start; - unsigned long end; -}; - static int migrate_vma_collect_hole(unsigned long start, unsigned long end, struct mm_walk *walk) @@ -2578,6 +2568,110 @@ restore: } } +/** + * migrate_vma_setup() - prepare to migrate a range of memory + * @args: contains the vma, start, and and pfns arrays for the migration + * + * Returns: negative errno on failures, 0 when 0 or more pages were migrated + * without an error. + * + * Prepare to migrate a range of memory virtual address range by collecting all + * the pages backing each virtual address in the range, saving them inside the + * src array. Then lock those pages and unmap them. Once the pages are locked + * and unmapped, check whether each page is pinned or not. Pages that aren't + * pinned have the MIGRATE_PFN_MIGRATE flag set (by this function) in the + * corresponding src array entry. Then restores any pages that are pinned, by + * remapping and unlocking those pages. + * + * The caller should then allocate destination memory and copy source memory to + * it for all those entries (ie with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE + * flag set). Once these are allocated and copied, the caller must update each + * corresponding entry in the dst array with the pfn value of the destination + * page and with the MIGRATE_PFN_VALID and MIGRATE_PFN_LOCKED flags set + * (destination pages must have their struct pages locked, via lock_page()). + * + * Note that the caller does not have to migrate all the pages that are marked + * with MIGRATE_PFN_MIGRATE flag in src array unless this is a migration from + * device memory to system memory. If the caller cannot migrate a device page + * back to system memory, then it must return VM_FAULT_SIGBUS, which has severe + * consequences for the userspace process, so it must be avoided if at all + * possible. + * + * For empty entries inside CPU page table (pte_none() or pmd_none() is true) we + * do set MIGRATE_PFN_MIGRATE flag inside the corresponding source array thus + * allowing the caller to allocate device memory for those unback virtual + * address. For this the caller simply has to allocate device memory and + * properly set the destination entry like for regular migration. Note that + * this can still fails and thus inside the device driver must check if the + * migration was successful for those entries after calling migrate_vma_pages() + * just like for regular migration. + * + * After that, the callers must call migrate_vma_pages() to go over each entry + * in the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag + * set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set, + * then migrate_vma_pages() to migrate struct page information from the source + * struct page to the destination struct page. If it fails to migrate the + * struct page information, then it clears the MIGRATE_PFN_MIGRATE flag in the + * src array. + * + * At this point all successfully migrated pages have an entry in the src + * array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst + * array entry with MIGRATE_PFN_VALID flag set. + * + * Once migrate_vma_pages() returns the caller may inspect which pages were + * successfully migrated, and which were not. Successfully migrated pages will + * have the MIGRATE_PFN_MIGRATE flag set for their src array entry. + * + * It is safe to update device page table after migrate_vma_pages() because + * both destination and source page are still locked, and the mmap_sem is held + * in read mode (hence no one can unmap the range being migrated). + * + * Once the caller is done cleaning up things and updating its page table (if it + * chose to do so, this is not an obligation) it finally calls + * migrate_vma_finalize() to update the CPU page table to point to new pages + * for successfully migrated pages or otherwise restore the CPU page table to + * point to the original source pages. + */ +int migrate_vma_setup(struct migrate_vma *args) +{ + long nr_pages = (args->end - args->start) >> PAGE_SHIFT; + + args->start &= PAGE_MASK; + args->end &= PAGE_MASK; + if (!args->vma || is_vm_hugetlb_page(args->vma) || + (args->vma->vm_flags & VM_SPECIAL) || vma_is_dax(args->vma)) + return -EINVAL; + if (nr_pages <= 0) + return -EINVAL; + if (args->start < args->vma->vm_start || + args->start >= args->vma->vm_end) + return -EINVAL; + if (args->end <= args->vma->vm_start || args->end > args->vma->vm_end) + return -EINVAL; + if (!args->src || !args->dst) + return -EINVAL; + + memset(args->src, 0, sizeof(*args->src) * nr_pages); + args->cpages = 0; + args->npages = 0; + + migrate_vma_collect(args); + + if (args->cpages) + migrate_vma_prepare(args); + if (args->cpages) + migrate_vma_unmap(args); + + /* + * At this point pages are locked and unmapped, and thus they have + * stable content and can safely be copied to destination memory that + * is allocated by the drivers. + */ + return 0; + +} +EXPORT_SYMBOL(migrate_vma_setup); + static void migrate_vma_insert_page(struct migrate_vma *migrate, unsigned long addr, struct page *page, @@ -2709,7 +2803,7 @@ abort: *src &= ~MIGRATE_PFN_MIGRATE; } -/* +/** * migrate_vma_pages() - migrate meta-data from src page to dst page * @migrate: migrate struct containing all migration information * @@ -2717,7 +2811,7 @@ abort: * struct page. This effectively finishes the migration from source page to the * destination page. */ -static void migrate_vma_pages(struct migrate_vma *migrate) +void migrate_vma_pages(struct migrate_vma *migrate) { const unsigned long npages = migrate->npages; const unsigned long start = migrate->start; @@ -2791,8 +2885,9 @@ static void migrate_vma_pages(struct migrate_vma *migrate) if (notified) mmu_notifier_invalidate_range_only_end(&range); } +EXPORT_SYMBOL(migrate_vma_pages); -/* +/** * migrate_vma_finalize() - restore CPU page table entry * @migrate: migrate struct containing all migration information * @@ -2803,7 +2898,7 @@ static void migrate_vma_pages(struct migrate_vma *migrate) * This also unlocks the pages and puts them back on the lru, or drops the extra * refcount, for device pages. */ -static void migrate_vma_finalize(struct migrate_vma *migrate) +void migrate_vma_finalize(struct migrate_vma *migrate) { const unsigned long npages = migrate->npages; unsigned long i; @@ -2846,124 +2941,5 @@ static void migrate_vma_finalize(struct migrate_vma *migrate) } } } - -/* - * migrate_vma() - migrate a range of memory inside vma - * - * @ops: migration callback for allocating destination memory and copying - * @vma: virtual memory area containing the range to be migrated - * @start: start address of the range to migrate (inclusive) - * @end: end address of the range to migrate (exclusive) - * @src: array of hmm_pfn_t containing source pfns - * @dst: array of hmm_pfn_t containing destination pfns - * @private: pointer passed back to each of the callback - * Returns: 0 on success, error code otherwise - * - * This function tries to migrate a range of memory virtual address range, using - * callbacks to allocate and copy memory from source to destination. First it - * collects all the pages backing each virtual address in the range, saving this - * inside the src array. Then it locks those pages and unmaps them. Once the pages - * are locked and unmapped, it checks whether each page is pinned or not. Pages - * that aren't pinned have the MIGRATE_PFN_MIGRATE flag set (by this function) - * in the corresponding src array entry. It then restores any pages that are - * pinned, by remapping and unlocking those pages. - * - * At this point it calls the alloc_and_copy() callback. For documentation on - * what is expected from that callback, see struct migrate_vma_ops comments in - * include/linux/migrate.h - * - * After the alloc_and_copy() callback, this function goes over each entry in - * the src array that has the MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag - * set. If the corresponding entry in dst array has MIGRATE_PFN_VALID flag set, - * then the function tries to migrate struct page information from the source - * struct page to the destination struct page. If it fails to migrate the struct - * page information, then it clears the MIGRATE_PFN_MIGRATE flag in the src - * array. - * - * At this point all successfully migrated pages have an entry in the src - * array with MIGRATE_PFN_VALID and MIGRATE_PFN_MIGRATE flag set and the dst - * array entry with MIGRATE_PFN_VALID flag set. - * - * It then calls the finalize_and_map() callback. See comments for "struct - * migrate_vma_ops", in include/linux/migrate.h for details about - * finalize_and_map() behavior. - * - * After the finalize_and_map() callback, for successfully migrated pages, this - * function updates the CPU page table to point to new pages, otherwise it - * restores the CPU page table to point to the original source pages. - * - * Function returns 0 after the above steps, even if no pages were migrated - * (The function only returns an error if any of the arguments are invalid.) - * - * Both src and dst array must be big enough for (end - start) >> PAGE_SHIFT - * unsigned long entries. - */ -int migrate_vma(const struct migrate_vma_ops *ops, - struct vm_area_struct *vma, - unsigned long start, - unsigned long end, - unsigned long *src, - unsigned long *dst, - void *private) -{ - struct migrate_vma migrate; - - /* Sanity check the arguments */ - start &= PAGE_MASK; - end &= PAGE_MASK; - if (!vma || is_vm_hugetlb_page(vma) || (vma->vm_flags & VM_SPECIAL) || - vma_is_dax(vma)) - return -EINVAL; - if (start < vma->vm_start || start >= vma->vm_end) - return -EINVAL; - if (end <= vma->vm_start || end > vma->vm_end) - return -EINVAL; - if (!ops || !src || !dst || start >= end) - return -EINVAL; - - memset(src, 0, sizeof(*src) * ((end - start) >> PAGE_SHIFT)); - migrate.src = src; - migrate.dst = dst; - migrate.start = start; - migrate.npages = 0; - migrate.cpages = 0; - migrate.end = end; - migrate.vma = vma; - - /* Collect, and try to unmap source pages */ - migrate_vma_collect(&migrate); - if (!migrate.cpages) - return 0; - - /* Lock and isolate page */ - migrate_vma_prepare(&migrate); - if (!migrate.cpages) - return 0; - - /* Unmap pages */ - migrate_vma_unmap(&migrate); - if (!migrate.cpages) - return 0; - - /* - * At this point pages are locked and unmapped, and thus they have - * stable content and can safely be copied to destination memory that - * is allocated by the callback. - * - * Note that migration can fail in migrate_vma_struct_page() for each - * individual page. - */ - ops->alloc_and_copy(vma, src, dst, start, end, private); - - /* This does the real migration of struct page */ - migrate_vma_pages(&migrate); - - ops->finalize_and_map(vma, src, dst, start, end, private); - - /* Unlock and remap pages */ - migrate_vma_finalize(&migrate); - - return 0; -} -EXPORT_SYMBOL(migrate_vma); +EXPORT_SYMBOL(migrate_vma_finalize); #endif /* defined(MIGRATE_VMA_HELPER) */ |